\hyper@anchorstart in draft mode wrong number of parameters

[lstonys]

Originally \hyper@anchorstart uses one parameter but in draft mode it is redefined to use two parameters (\def\hyper@anchorstart#1#2{#2\Hy@xspace@end}) and here comes bug with natbib.

\documentclass{book}
\usepackage{natbib}
\usepackage[draft]{hyperref}
\begin{document}
\begin{thebibliography}{1}
\bibitem[{Awwad(2016)}]{sss}
x
\end{thebibliography}
\end{document}

Tracing shows that \hyper@anchorstart is with one parameter but expects two:

\hyper@natanchorstart #1->\Hy@raisedlink {\hyper@anchorstart {cite.#1}}
#1<-sss\@extra@b@citeb 

\Hy@raisedlink ->

\hyper@anchorstart #1#2->#2\Hy@xspace@end 
#1<-cite.sss\@extra@b@citeb 
! Argument of \hyper@anchorstart has an extra }.
<inserted text> 
\par 

[u-fischer]

I get no error in a current TeX live.

[lstonys]

I used TL2024 but checked in the repository that it is still the same \hyper@anchorstart redefinition:

\Hy@AtBeginDocument{%
  \ifHy@draft
    \let\hyper@@anchor\@gobble
    \gdef\hyper@link#1#2#3{#3\Hy@xspace@end}%
    \def\hyper@anchorstart#1#2{#2\Hy@xspace@end}%
...

So now I tried with the newest:

This is LuaTeX, Version 1.24.0 (TeX Live 2026)  (format=dvilualatex 2026.6.5)  29 JUL 2026 20:23

Did you use dvilualatex?

[u-fischer]

ah, dvi mode. Yes there is an error. I will try to look later. But be aware that the command reinserts the second argument, so grabbing two is by purpose and with the pdflatex it works fine.